Colorado Avalanche star Nathan MacKinnon sustained a lower-body injury in the second period of Monday night's 3-1 loss to the Los Angeles Kings and did not return.
Coach Jared Bednar did not know the extent of the injury or when it happened.
"He leaves the game, I'm concerned right away,'' Bednar said postgame. "I know that he wasn't good enough to come back in the game tonight, so yeah, I'd say that is concerning.''
MacKinnon had one shot in 11:37 of ice time before departing in the second frame.
He has 35 goals and 58 assists this season, good for a tie for fourth in the league in points entering Monday.
The Associated Press contributed to this report.